1. Field of the Invention
The present invention relates to a gas turbine engine, and more particularly, to the support for a bearing in the turbine portion of the engine, downstream of the combustion chamber.
2. Description of the Prior Art
Such supports are by the nature of their location subject to thermal differentiation. For example, in a typical gas turbine engine, the bearing supports in the so-called hot portion of the engine, include radially extending tension rods or fairings attached to the outer casing and passing through the annular gas exhaust duct to engage a bearing support housing centrally of the engine. The fairings which pass through the annular exhaust gas passage and the inner casing are, of course, subjected to very high temperatures while the bearings per se are usually in a bath of cooling medium. The bearing support is a structural intermediate between these two thermal extremes. The bearing support must also be capable of compensating for radial thermal expansion due to the higher temperatures of the parts near the annular exhaust gas passages and much less radial expansion of the parts near the cooler bearing region.
It is customary to assemble the bearing support parts with a very tight radial fit such that they will still maintain their position under hot conditions. It is also known to provide radial dowels or pins to allow for radial expansion and thus loosening of the parts without loss of structural stability.
U.S. Pat. No. 2,829,014, H. May, issued Apr. 1, 1958 to United Aircraft Corporation, suggests the use of a spring ring intermediate between the bearing support rods which pass through the exhaust gas path and which are supported by the outer casing and the bearing support. The points of contact between the spring ring and the above element are staggered.
U.S. Pat. No. 2,928,648, Haines et al, issued in 1960 to United Aircraft Corporation, describes tension rods extending directly from the bearing housing to the outer casing and any radial resilience is obtained from the outer casing.